Toshiba A75-S2111 UDMA5 instead of 6

Hi, I just picked up this laptop for super cheap has a radeon 9000/9100 chipset which im sure supports udma-6 and the hard drive is a 80gb hitachi travelstar. Both support udma 6 only problem is the system says max supported is udma-5. I can't seem to locate specific south bridge driver for this lappy. Im not sure how to get udma-6 going.